Re:Re:Re:Re:Re:Re:Help Help P0032 FIXED!!!!!

Hello Guys

I use Nissan Sentra 2008, since last month am having trouble code P0032.
Have changed 02 sensor multiple times which didn't fix it.
Probe further as I understand it may be circuit problem.
Used FSM / wiring diagram to checked all the wiring, they are all in good shape and have continuity except the signal wire which has 12v+ just as the dedicated power wire 12v+, I know it's not normal.
I thought I was having short to power but checked the signal wire all way through and there is no wire coming in contact with it.

I have a four wire harness and 02 sensor

2 being heater wires ( + and -)
1 signal wire
1 power wire 12v

Why is signal wire having 12v on KOEO?
Do anyone know the reference volt for the signal wire?
It's hurting my fuel economy since ECM thing the signal is high therefore throwing more fuel.

Help me guys

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2008 Sentra but which engine? Is this by any chance a Wideband sensor? What are the wire colors? can you post colors and voltage? Also, if you can re-send that wiring diagram a bit larger, it would be easier to read.

Check the signal voltage at the pcm with it unplugged. Should be 5v. If it is the signal wire is shorted to a 12v source. Don't forget to inspect the sensor plug pins for rust. What is the voltage on the ground wire?

washer wrote: 2008 Sentra but which engine? Is this by any chance a Wideband sensor? What are the wire colors? can you post colors and voltage? Also, if you can re-send that wiring diagram a bit larger, it would be easier to read.

2.0l Petrol engine
Yes, its a wideband sensor
Brown with white stripe -BR/W (Signal Wire to ECM/PCM=12 volts)
Red with black stripes-R/B(Dedicated power wire=12 volts)
Blue with green stripes-L/G(Heater wire-Negative=2.2 volts)
Blue with red stripes-L/R (Heater wire-Positive=1.8 volts)

The voltage are taken on KOEO basis

Sure, wiring diagram attached

scannerjohn wrote: Check the signal voltage at the pcm with it unplugged. Should be 5v. If it is the signal wire is shorted to a 12v source. Don't forget to inspect the sensor plug pins for rust. What is the voltage on the ground wire?

Sure, i unplugged the 02 harness and KOEO the signal wire is 12 volts (Have checked for short power and ground cant see any), wire is not melted or whatsoever.

The sensor or harness plug pins is not rusted, sprayed electrical cleaners to them already.

Which one is the ground wire?
Can you help with the FSM/Wiring diagram i have attached to direct me?

Can it be a bias voltage? If yes can a bias voltage throw 12 volts on KOEO at signal wire

The Brn/Wht wire is the heater control. If you are measuring 12v on the Br/w wire, with the sensor disconnected, it is possible that you are seeing a bias voltage. To test this, take an incandescent test-light, connected to ground, and touch the heater control (Br/w) wire with the test-light probe. If it is a bias voltage the test light will NOT light, and the voltage will drop to near zero. If the heater control wire is shorted to power, the test-light will illuminate.

Hello

This is done at KOEO or engine running ?

Should I connect the 02 sensor to the harness while doing this and backprobe it.

What's the name of the wire coming from the IPDM to ECM/ PCM terminal 3; that has constant 12v.

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Mariowinax1 wrote: This is done at KOEO or engine running ?

Should I connect the 02 sensor to the harness while doing this and backprobe it..

The test recommended by Chad is KOEO with the sensor unplugged. If you try it plugged in the heater will pass more than enough current to illuminate a test light.

Mariowinax1 wrote: What's the name of the wire coming from the IPDM to ECM/ PCM terminal 3; that has constant 12v.

If you mean the red and brown wire from IPDM to the AFR terminal 4 t's the power feed for the heater. 12V is good for that wire. If it's a power feed from the IPDM direct to the ECM I wouldn't worry about that for now.

Voltage readings you took on the blue signal wires also appear to be correct, and shouldn't have anything to do with a heater code according to SI.

This is done at KOEO or engine running ?...Should I connect the 02 sensor to the harness while doing this and backprobe it.

KOEO, sensor connector disconnected.

What's the name of the wire coming from the IPDM to ECM/ PCM terminal 3; that has constant 12v.

I don't see a wire going from the IPDM to ECM Pin 3. The only wire coming from the IPDM is the Heater Power.


ECM Pin 3 is the BR/W Heater Control wire. If the sensor is disconnect, it may have a 12 volt bias. Test for this with a test-light, as I have described.

If the sensor is CONNECTED, and the ECM has NOT energized the heater circuit, KOEO you will read the 12v, from the Heater Power, coming THROUGH the heater element, waiting for a ground from the ECM.



When the ECM energizes the Heater circuit, it applies a GROUND to the Heater control wire.

Lot of info to digest. Heater circuit is controlled by ecm which get signal from temp sensor to apply voltage. Check your temp sensor. P0032 high voltage suggest that temp sensor is sending signal to ecm that engine temp is cold so ecm continues to send 12v to heater circuit.

Yes

Exactly my point; think there is underlying problem aside the heater circuit

An unplugged/ defective 02 sensor is most likely to throw these codes P1148, P0031.

P0032 whiles 02 sensor is unplugged/ defective is weird.

Will test the heater circuit tomorrow and revert back with feedbacks.

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Chad wrote: When the ECM energizes the Heater circuit, it applies a GROUND to the Heater control wire.

You know it's gettin' serious when we break out the crayons :silly:

According to SI it ain't that simple. Looks to be PWM control so you'll never measure 0V on the control wire. Also sounds like there is a shunt inside the ECM with voltage sensing upstream of it. That sensed voltage being too high is what pops the P0032. If the control wire isn't shorted to power ECM grounds would be the next thing to go after. After that are the replacement AFRs OEM or aftermarket?

Yes, the heater wire is PWM. Is your model CA or federal emissions? Is it possible you have the wrong part in there?

Heater + is connected to a Diode in ecm. The diode off on is controlled by temp and load input. Diode is not getting signal to allow v to ground so is staying high.

CA

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Update

1. As I was about starting circuit test, I discovered 02 sensor fuse was blown, this is the second in a week i am repacing it when this trouble code P0032 started.

2. When 02 sensor is unplugged, test light grounded , positive power directed to pcm/pwm/ heater control wire on KOEO there is 0 volts by multimeter.
Test light directed to control wire is not lighted but to power feed obviously light it.

When 02 is plugged, heater control wire comes with 12 volts alongside the dedicated power feed coming from ipdm.
In my opinion I think this is the bias volt, if the pcm actuate the signal wire heater control, it will set the ground for power feed which is not working at the moment.
This is where we are battling for it to work.

3. Playing around it, I connected the 02 sensor to the harness, backprobe the wiring.
Used the test light to connect both signal wires according to the FSM/SI/Wiring diagram; monitoring on my obd, 02 sensor started working and entered into close loop (CL), when the test light was disconnected from the two signal wires the PCM get back to Open Loop (OL)

4. Let ne confirm this, wideband 4 wire 02 sensor is working; tested it, thats definitely not the fault we are looking at causing P0032
Ohms is ~2.9
Heater wires of it has continuity.

5. I checked the ECT in the morning before starting to work on it.
ECT (Engine Coolant Tenp) was 100.4F whiles IAT (Intake Air Temp) has 123.8F
Normal?
BTW, I intermittently have ECT codes but its goes away by itself.
The code that explains that engine is running cold.
According to the SI/Wiring diagram the sensors the actuate the heater control wire to set the ground are Engine Speed (Crankshaft Position Sensor) and Amount of intake air (Mass airflow sensor) not ECT. Help me if am wrong.

6. Loosed, cleaned and retighten dedicated grounds for the 02 sensor as well.

Guys with this any clue or my next direction nailing this problem down?
I have a budget obd Bluetooth device i use as a diyer, if you like any data pids let me know so I get it to you.


Really appreciate your efforts in aiding me fix this problem.

Much love

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Standing by..

Have you done a visual inspection of the wires to make sure there isn't a short to ground on the power side somewhere that's causing that fuse to blow? Push and pull on the harness and all of that?

Is it that warm there in the morning? I would expect the temps to be closer to each other, and near ambient.

Did you have a p0128 before? If your thermostat isn't sticking open or your ECT sensor wonky, there may be a bulletin that addresses that code with an ECM update. I'm not 100% sure if it applies to that year though.

Do those temperatures change when it warms up to believable numbers?

Not sure if it could be tied to what scannerjohn was saying about the diode.

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Couple of things to start with that seem wrong. First you should not be blowing fuses on the O2 circuit. Somewhere along that wire it is touching to ground.

Second the engine temp is high. Is the temp where your at 100 degrees? Same goes for the intake air temp. Unless it HOT outside these temps should reflect ambient temps.

I know you asked more questions but these three must be fixed first.

Keep me posted.